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41.
Kohzuma T Kikuchi M Horikoshi N Nagatomo S Kitagawa T Czernuszewicz RS 《Inorganic chemistry》2006,45(21):8474-8476
A copper-containing nitrite reductase from Alcaligenes xylosoxidans NCIMB 11015 has its own unique blue or type 1 copper protein resonance Raman spectrum in the usual Cu-S(Cys) stretching region, nu(Cu-S(Cys)), with a pair of strong peaks at 412 and 420 cm(-1) and a weak peak at 364 cm(-1). The predominantly nu(Cu-S(Cys)) Raman bands at 412, 420, and 364 cm(-1) of the type 1 copper site all shifted to higher frequencies upon binding of nitrite to the type 2 copper site, and the resonance Raman difference spectra progressively intensified with the increments of nitrite ion concentration. Positive support for substrate binding to the type 2 copper is provided by the nu(Cu-S(Cys)) bands in the resonance Raman spectrum of a type 2 copper-depleted enzyme, which is insensitive to the presence of NO2-. The shift to higher frequency of the Raman bands of the type 1 copper center with the addition of nitrite ions suggests a stronger Cu-S(Cys) interaction in the substrate-bound A. xylosoxidans nitrite reductase. 相似文献
42.
Saravanan G Hara T Yoshikawa H Yamashita Y Ueda S Kobayashi K Abe H 《Chemical communications (Cambridge, England)》2012,48(60):7441-7443
Intermetallic Pt(3)Ti nanoparticles are solubilized in water by using a generation-five, hydroxyl-terminated, poly(amidoamine) dendrimer, G5OH, as a post-synthesis surfactant. Pt(3)Ti nanoparticles, encapsulated in G5OH and dispersed over the electrode surface, exhibited a superior catalytic activity toward the electro-reduction reaction of oxygen compared to as-prepared, highly agglomerated nanoparticles. 相似文献
43.
Arichi N Inase A Eto S Mizukoshi T Yamamoto J Iwai S 《Organic & biomolecular chemistry》2012,10(11):2318-2325
The (6-4) photoproduct is one of the major damaged bases produced by ultraviolet light in DNA. This lesion is known to be alkali-labile, and strand breaks occur at its sites when UV-irradiated DNA is treated with hot alkali. We have analyzed the product obtained by the alkali treatment of a dinucleoside monophosphate containing the (6-4) photoproduct, by HPLC, NMR spectroscopy, and mass spectrometry. We previously found that the N3-C4 bond of the 5' component was hydrolyzed by a mild alkali treatment, and the present study revealed that the following reaction was the hydrolysis of the glycosidic bond at the 3' component. The sugar moiety of this component was lost, even when a 3'-flanking nucleotide was not present. Glycosidic bond hydrolysis was also observed for a dimer and a trimer containing 5-methyl-2-pyrimidinone, which was used as an analog of the 3' component of the (6-4) photoproduct, and its mechanism was elucidated. Finally, the alkali treatment of a tetramer, d(GT(6-4)TC), yielded 2'-deoxycytidine 5'-monophosphate, while 2'-deoxyguanosine 3'-monophosphate was not detected. This result demonstrated the hydrolysis of the glycosidic bond at the 3' component of the (6-4) photoproduct and the subsequent strand break by β-elimination. It was also shown that the glycosidic bond at the 3' component of the Dewar valence isomer was more alkali-labile than that of the (6-4) photoproduct. 相似文献
44.
Multilayer graphene was prepared by mechanical exfoliation of natural graphite with dioctyl phthalate(DOP) as milling medium without solvent. The obtained mixture could be directly mixed with poly(vinyl chloride)(PVC) for melt-forming, with DOP acting as plasticizer and graphene acting as conductive filler for antistatic performance. The composite showed surface resistance of 2.5 ×10~6 Ω/□ at 1 wt% carbon additive, significantly lower than approx. 7 wt% of raw graphite required for achieving the same level. This value is low enough for practical antistatic criterion of 3 × 10~8 Ω/□. The effect of filler addition on mechanical performance was minimal, or even beneficial for the milled carbon in contrast to the case of raw graphite. 相似文献
45.
Roongsawang N Hase Ki Haruki M Imanaka T Morikawa M Kanaya S 《Chemistry & biology》2003,10(9):869-880
Arthrofactin is a potent cyclic lipopeptide-type biosurfactant produced by Pseudomonas sp. MIS38. In this work, an arthrofactin synthetase gene cluster (arf) spanning 38.7 kb was cloned and characterized. Three genes termed arfA, arfB, and arfC encode ArfA, ArfB, and ArfC, containing two, four, and five functional modules, respectively. Each module bears condensation, adenylation, and thiolation domains, like other nonribosomal peptide synthetases. However, unlike most of them, none of the 11 modules possess the epimerization domain responsible for the conversion of amino acid residues from L to D form. Possible L- and D-Leu adenylation domains specifically recognized only L-Leu. Moreover, two thioesterase domains are tandemly located at the C-terminal end of ArfC. These results suggest that ArfA, ArfB, and ArfC assemble to form a unique structure. Gene disruption of arfB impaired arthrofactin production, reduced swarming activity, and enhanced biofilm formation. 相似文献
46.
This paper studies an initial boundary value problem for a one-dimensional isentropic model system of compressible viscous gas with large external forces, represented by v
t
–u
x
=0,u
t
+(av
–)
x
=(u
x
/v)
x
+f(
0
x
vdx,t), with (v(x, 0),u(x, 0))= (v
0(x),u
0(x)),u(0,t)=u(1,t)=0. Especially, the uniform boundedness of the solution in time is investigated. It is proved that for arbitrary large initial data and external forces, the problem uniquely has an uniformly bounded, global-in-time solution with also uniformly positive mass density, provided the adiabatic constant (>1) is suitably close to 1. The proof is based on L
2-energy estimates and a technique used in [9]. 相似文献
47.
Shigenori Matsumoto 《Bulletin of the Brazilian Mathematical Society》1997,28(1):89-101
We consider the rotation setR of a homeomorphismf, isotopic to the identity, of a closed surface of genusg2. We show if Int(R) is nonempty and contains an element which is realized by an asymptotic measure, then all the rational points of Int(R) are realized by periodic orbits. We raise an example to show that the second condition above is indispensable ifg2. We also show that ifR contains a (g+1)-simplex whose vertices are realizable by periodic orbits, then the topological entropy off is positive. 相似文献
48.
49.
Shigenori Kamada Hirotaka Nomoto Katsutoshi Fukuda Tadashi Fukawa Hirofusa Shirai Mutsumi Kimura 《Colloid and polymer science》2011,289(8):925-932
A facile and scalable preparation of dispersion of isolated graphene in various organic solvents has been developed by combining
between covalent and noncovalent functionalizations of the graphene surface. Covalently functionalized graphene (FRG) was
prepared by the reaction of partially reduced graphene oxide with aryl diazonium salts, followed by the graphene oxide being
completely reduced with hydrazine. The resulting FRG disperse readily in organic solvents such as N,N′-dimethylformamide (DMF) and N-methyl-2-pyrrolidinone and the functionalization of graphene was characterized by Fourier transform infrared spectroscopy,
thermogravimetric thermogram, X-ray photoelectron spectroscopy, and Raman spectroscopy. The hydrophobic surface of FRG was
noncovalently wrapped with aromatic hexakis-dodecylhexa-peri-benzocorone (HBC) by simply mixing of dispersion of FRG in DMF with toluene solution of HBC. The complexation of FRG and
HBC was monitored by viewing the absorption and fluorescence spectral changes. Atomic force microscopic images confirmed that
graphene was covalently and noncovalently functionalized, while keeping a two-dimensional sheet shape. 相似文献
50.
Yamaguchi S Nagatomo S Kitagawa T Funahashi Y Ozawa T Jitsukawa K Masuda H 《Inorganic chemistry》2003,42(22):6968-6970
A novel copper(II)[bond]OOH complex with functional ligand that can form a hydrogen bond with the distal oxygen of hydroperoxide has been designed and prepared as a structural/functional model of dopamine beta-hydroxylases, whose spectroscopic characterization and decomposition rates have indicated that the hydroperoxide is activated through the hydrogen-bonding interaction with the distal oxygen. 相似文献